This invention relates generally to the manufacture of shaped plastic trim panels and more particularly to an apparatus and method for molding a shaped plastic trim panel such as an automotive headliner, and trimming the panel while it is still in the mold.
One type of headliner is made from a wet moldable composite comprising a sheet of foam that is impregnated with an uncured liquid plastic material such as a thermal setting urethane precursor. The sheet of wet moldable composite is placed in an open compression mold in a hydraulic press. The press closes the mold to shape the composite sheet and cure the plastic material under appropriate heat and pressure. The shaped composite is then demolded and taken to another location where it is trimmed in a secondary operation. This method of molding and trimming the headliner in different operations is costly and time consuming.
U.S. Pat. No. 3,377,658 granted to Paul Junior Wilhoit and Gerald Kenneth Miller Apr. 16, 1968 discloses a carpet press mold and trimmer for molding contour matching floor carpets for automobiles. The press has a fixed lower mold and a moveable upper mold. The molds have continuous, generally rectangular cutting slots that are aligned when the mold is closed. Four traveling cutters project into the aligned slots and travel along the aligned cutting slots to trim the carpet while it is still in the mold. A compression ring located outside the cutting slots holds the peripheral portions of the carpet down during the cutting operation to increase the accuracy of the trim.
This method eliminates the need for trimming the carpet in a secondary operation which reduces manufacturing time and expense. However, the solution is not entirely satisfactory because the cutters must travel the periphery of the carpet after it is shaped in the molding press so that the trimming operation takes considerable time. Moreover, several cutters are involved which adds to the expense and complication of the operation. Another drawback is that the compression ring relies on the force of gravity to hold the outer peripheral portions of the carpet during the cutting operation. The compression ring is extremely heavy and difficult to manipulate which adds further cost and complexity to the cutting operation.
U.S. Pat. No. 4,328,067 granted to Franco Cesano May 4, 1982 discloses a method and apparatus for molding and laminating an automotive door panel in a heated press and for trimming the door panel while it is still in the press. This method and apparatus employs an annular element that has a cutting edge that cooperates with a shearing edge to trim a substrate layer and a secondary blade that cooperates an upper surface of the annular element to trim a coating layer.
This trimming operation is quicker than the travelling cutters used in the carpet trimming operation discussed above. However, neither the peripheral portion of the substrate layer nor the peripheral portion of the coating layer are held down outwardly of the cutting tools during the trimming operation. This reduces the accuracy and neatness of the cut. Such a trimming operation may be satisfactory for a laminated door panel where the trimmed edge of the substrate layer is wrapped by free margin portions of the coating layer. The accuracy and neatness of the cut edges of the substrate layer and the coating layer is not important because the cut edges of the substrate layer are covered by the margin portions of the coating layer and the cut edges of the coating layer are on the back side of the substrate layer.
Thus while this trimming operation is satisfactory for some purposes, it is not entirely satisfactory for in-mold trimming of trim panels such as automotive headliners that are made from a wet moldable composite rather than a laminate because these trim panels require cut edges that are accurate and neat.